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Bad news for corals and divers.

By JW Dowey - 07 Oct 2014 8:30:0 GMT
Bad news for corals and divers.

The Porites corals dominate near Hawaii, here sheltering a school of Anthias; Porites image; Credit: © Shutterstock

The corals of Hawaii, specifically in Papahanaumokuakea Marine National Monument, represent the great majority of coral with US jurisdiction. They are represented largely by Porites, mainly P. lobata and P. compressa. Montipora and Pocillopora species make up most of the other dominants on the reefs. The loss of many corals in the Pacific Ocean this summer, due to warm sea surface temperatures, is a potential disaster. Recovery is vital. The previous loss of Caribbean corals, and of course the multiple species of animal and plant that need the coral, are explained in this article: Coral Cover’s Deadly Decline.

Oahu has been badly hit at numerous points, while, even 1000 miles northwest, mass bleaching has occurred at Lisianski atoll, with lesser events at Midway, Pearl and Hermes atolls. Courtney Crouch is a researcher at Hawaii Institute of Marine Biology, so when she calls the situation dire, it’s probably true! 35% of the sites have been bleached.

The cause of bleaching is accepted nowadays as being thermal and this was the warmest summer for 50 years. The algal symbionts within coral are lost after 8 weeks of high-temperature-induced stress but can return if the bleaching doesn’t continue too long. Unfortunately, it will be October before temperatures lower, so more profound deterioration is possible. El Nino is held responsible, moving the warm water north as the summer progresses.

The last time this happened was in 2002 and 2004. Last week, along the windward coasts of Oahu, the Hawaii Department of Land Resources rapid response team examined the damage. Among them administrator Frazer McGilvray reported the corals as appearing, “snow white.” This entails a moderate to severe bleaching event, needing careful monitoring and avoidance of the corals by ocean users such as divers. Photographs will be needed though, to keep the authorities up-to-date with the situation, day to day. Here is NOAA’s coral watch tool if you can help or want to view the Coral bleaching map.